Research



"Nanotechnology is the marriage

of chemical synthetic talent

with a direction provided

by "device-driven" ingenuity

coming from engineering"



Roald Hoffmann, Nobel Laureate in Chemistry








This page contains an overview of our research activities. For more detailed and updated information you may take a look at our publications.


Introduction

From a functional point of view molecular devices can be used for many purposes, including chemical catalysis, medical diagnostics and therapy, materials science, electronics, etc. Our interest is focussed on three main categories of molecular devices:

Devices that can be used to collect, transform, and store information: among these systems are chemosensors, switches, antennas, logic gates and circuits, memories.

Devices for the conversion of solar energy: nanoscale antennas, molecular batteries, systems for photoinduced charge separation.

Devices that exhibit mechanical motion at the nanoscale: molecular machines, gears and motors

Systems of this kind can be constructed from several types of chemical structures. In our group we are particularly interested in host-guest systems, interlocked compounds (rotaxanes, catenanes, and related species), transition-metal complexes, multicomponent molecules (dendrimers), liposomes, and semiconductor nanocrystals (quantum dots).

Many of the investigated systems exhibit a high degree of structural complexity, which can result in a rich functional behaviour. The inherent challenges associated with the experimental investigation of complex species and the rationalization of their behaviour are intellectually and technically stimulating and hold great promise for the progress of basic science. Nevertheless, we are aware that any future real world application of nanoscale devices will rely on their availability on relatively large scales, which in turn depends strongly on whether they can be easily synthesized. The development of structurally unsophisticated chemical systems capable of performing valuable tasks is therefore very important to foster practical applications. We firmly believe that simplicity and minimalist design approaches, whenever possible with regard to the desired functionality, are extremely important added values for nanodevices.


Research themes

The leitmotiv of our scientific work is the design, synthesis and photophysical, photochemical and electrochemical investigation of molecular and supramolecular systems capable of performing useful functions and that, as such, can be viewed as examples of devices and machines at the molecular level. Our activities can be categorized in four themes, which are briefly described below. For more details, please look at our Publications page.


Molecular and supramolecular systems for information processing

Miniaturization has been an essential ingredient in the outstanding progress of information technology over the past fifty years. The next, perhaps ultimate, limit of miniaturization

is that of molecules, which are the smallest entities with definite and programmable size, shape, and properties. Molecular-level systems that respond to external stimulation by changing some physical or chemical properties can be viewed as input-output devices and therefore may be useful for gathering, transferring, processing, and storing information.


Some of these nanoscale devices can, in fact, perform logic operations of remarkable complexity. This research - although still far from being transferred into technology - is attracting interest, since the nanometer realm seems tobe out of reach for the "top-down" techniques currently available to the microelectronics industry.


Among the examined systems are molecular switches, sensors, wires, plug/socket devices, extension cables, memories, and combinational and sequential logic circuits. These functionalities are implemented using a large variety of chemical species, from unsophisticated molecules to transition-metal complexes, supramolecular assemblies and molecule-nanocrystal hybrids. Particular attention is devoted to the concepts of logic superposition and reconfiguration, which can lead to a substantial degree of functional integration. We are also interested at developing strategies for the serial connection (cascading) of distinct molecular logic systems. 

Leaving aside futuristic speculations related to the construction of a chemical computer, molecular logic devices could be interesting for specific applications in areas such as diagnostics, medicine, and materials science, where problems need to be addressed in places - for example, inside a cell - that are out of reach for a silicon-based computer.






Chemically functionalized quantum dots

Quantum dots (QDs) are inorganic nanoparticles whose opto-electronic properties are determined by the quantum confinement of the charge carriers. Since the development of synthetic methods in solution in the 90s, it has become clear that these nanoparticles represent a valid alternative to molecular fluorophores for applications including chemical and biological sensing, diagnostic imaging, electroluminescent devices and solar cells. QDs are characterized by large molar absorption coefficients in the UV-visible, and an intense emission band with a narrow spectral profile that can be accurately positioned in a spectral region ranging from blue to near IR by adjusting the chemical composition and the size of the particles. These properties, together with a high thermal and photochemical stability, and versatile surface functionalization, render QDs appealing components for the construction of photoactive molecule-nanocrystal hybrids.


Our actitivity deals with the size-controlled synthesis of QDs of various materials (MX, with M = Cd, Zn and X = O, S, Se, Te), and the investigation of both their basic properties and their interaction with functional molecular species (receptors, guests, redox-active species, chromophores, photochromes, etc.). Because of the environmental problems posed by Cd-based materials, we are particularly interested to develop and employ highly emissive cadmium-free quantum dots.



The final purpose of this research is to modify the electro-optical properties of the QDs and implementing functionalities (e.g., luminescence switching) by exploiting nanocrystal-molecule interactions. The functional molecules can be either non-specifically embedded in the monolayer of the capping ligands, linked to the nanocrystal by means of non-covalent supramolecular strategies, or covalently attached to the QD surface.


Mechanical molecular machines

The design, synthesis, and operation of supramolecular (multicomponent) systems capable of performing specific, directional mechanical movements under the action of a defined energy input - namely, molecular machines - constitute a fascinating challenge in the field of nanoscience. Such a daring goal finds its scientific origin in the existence of natural molecular machines, although it is clear that the construction of systems of such structural and functional complexity by using the bottom-up molecular approach would be, at present, a prohibitive task. Therefore, what can be done is to synthesize simple artificial prototypes consisting of a few molecular components capable of moving in a controllable way, and to investigate the challenging problems posed by interfacing such nanodevices with the macroscopic world, particularly as far as energy supply and information exchange are concerned. In recent years synthetic talent combined with a device-driven ingenuity evolved from chemists’ attention to functions and reactivity, have led to outstanding achievements in this field.

In this context, we are interested in the design, synthesis and study of multicomponent species (in most cases interlocked compounds such as rotaxanes, catenanes and related species) capable of performing mechanical motions of their molecular components in response to external stimulation (addition of chemical reactants, application of electric potentials, light irradiation).


We have investigated examples of pH-driven and sunlight-powered molecular shuttles, molecular elevators, and catenane rotary devices. An important scientific objective of this research is to gain a deep understanding on the operating mechanisms of such systems, thereby learning how to design new prototypes with novel functionalities and/or improved performance.


We are particularly interested in the investigation of molecular machines capable of dissipating an energy source to operate away from chemical equilibrium, a research that led us to develop the first example of an artificial molecular pump powered by light. For more information on this topic, follow this link.


The final aim is the construction of mechanical nanodevices that can carry out useful functions such as memorizing/processing information in binary form, control of membrane permeability, uptake and release of other molecules, up to mechanical actuation on the micro- and macroscopic scales (molecular muscles).












Basic photochemistry, electrochemistry, and supramolecular chemistry

The objective of this research line is to gain basic knowledge on the properties of molecules, supermolecules, and nanoparticles, and on fundamental physico-chemical processes. The investigated topics are:
- thermodynamic and kinetic aspects of self-assembly reactions of host-guest systems
- photoinduced energy- and electron-transfer processes
- photoisomerization reactions in azobenzene-type species and other photochromes
- chemiluminescent and electrochemiluminescent reactions
- photophysical and redox behaviour of organic molecules and metal complexes
- photocatalytic properties of nanostructured surfaces
- photophysical and redox behaviour of inorganic nano particles
- photoactive solid materials



In the frame of this research line, we reported the first example of a nanoporous molecular crystal based on shape-persistent azobenzene tetramers, in which porosity and crystallinity can be switched off and on by light irradiation and heating, respectively. We showed that this material can selectively adsorb carbon dioxide from the gas phase by hosting it in the inner cavities, and that light irradiation causes the release of the CO2 molecules owing to the collapse of the pores. For more information about this topic, follow this link.

Experimental activities

Many of our systems are designed and synthesized in our laboratories, where we can perform both organic and inorganic syntheses. We also enjoy studying the compounds made by other research groups specialized in synthetic chemistry, in the frame of our collaborations.

In most instances our experiments take place in homogeneous solution; however, we also work with species immobilized in frozen or polymer matrices, and deposited onto solid optical surfaces or electrodes. Occasionally we study the photophysical properties of compounds in the solid state. We are very interested on water-soluble vesicles (typically, liposomes) as nanocontainers for the construction of compartmentalized systems wherein functional molecular species can be introduced either in the membrane bilayer or in the inner (or outer) aqueous phase.


For a description of the infrastructures, equipment and techniques that we employ in our research, please visit the Lab tour page.









Funding agencies

Our research is, or has been, funded by the following agencies and institutions:

European Union (FP6, FP7, Horizon2020, European Research Council), United Nations Development Office, Ministero dell'Istruzione, Universita' e Ricerca (PRIN, FIRB), Ministero degli Affari Esteri (DGPSP), Universita' Italo-Francese (Galileo program), Regione Emilia-Romagna (PRIITT, Spinner), Fondazione Carisbo, Universita' di Bologna (Progetti Strategici, Istituto di Studi Avanzati)




Ongoing projects


European Research Council - Advanced Grant 2015

Light effected autonomous molecular pumps: Towards active transporters and actuating materials (LEAPS)

Principal investigator, 2016-2021


Università Italo-Francese - "Vinci" Programme

Development of functionalized quantum dots for photoinduced applications in nanomedicine

Co-tutelled doctorate fellowships (coordinator), 2014-2016


Università di Bologna - Fondo di Ateneo per la Ricerca di Base

SLaMM - Spin labelled molecular machines

FARB linea 2 (coordinator), 2014-2016


Ministero dell'Istruzione, Università e Ricerca

InfoChem - Integrated supramolecular technologies for chemical information processing: advanced molecular devices and materials

PRIN Project, 2010 call (deputy coordinator), 2013-2016




Concluded projects



Ministero dell'Istruzione, Università e Ricerca
InfoChem - Integrated supramolecular technologies for chemical information processing: advanced molecular devices and materials
PRIN Project, 2010 call (deputy coordinator), 2013-2016


Regione Emilia-Romagna - Consorzio Spinner 2013
Nano-Biomed-Light: Sistemi molecolari e materiali fotoresponsivi per applicazioni nano- e bio-tecnologiche e in oncologia
Spinner doctorate fellowships, 2012-2014

European Commission - 7th Framework Programme - Nanotechnology, materials and processes
HYSENS - Hybrid Molecule-Nanocrystal Assemblies for Photonic and Electronic Sensing Applications
SMALL Collaborative project (local coordinator), 2011-2013

Ministero degli Affari Esteri
Self-assembling luminescent semiconductor nanocrystals for analytical and materials science applications
Bilateral project of national relevance with South Korea (coordinator), 2010-2011

Ministero dell'Istruzione, Università e Ricerca
Sistemi supramolecolari per la costruzione di nanomacchine, elaborazione di segnali, sensing e catalisi
PRIN Project, 2008 call, 2010-2011   

Università Italo-Francese - "Galileo" Programme
Chemically modified luminescent semiconductor quantum dots
Project for mobility of researchers (coordinator), 2009

Regione Emilia-Romagna
PROMINER-Progetto per le micro e nano tecnologie in Emilia Romagna
PRIITT NetLab project (local coordinator), 2008-2010

Università di Bologna
Compositional and Executable Representations of Nano Devices
Strategic project of the University (local coordinator), 2006-2009

Ministero degli Affari Esteri
Light actuated molecular engines based on luminescent rotaxanes
Bilateral project of national relevance with China (coordinator), 2006-2009

European Commission - 6th Framework Programme - Priority 3
BIOMACH: Molecular machines – Design and nano-scale handling of biological antetypes and artificial mimics
STREP Project, 2004-2007

Regione Emilia-Romagna
Trattamento superficiale per fotocatalisi destinato alla depurazione dell'aria e dell'acqua mediante differenti tecnologie di deposizione
PRIITT - SME Collaborative research project (local coordinator), 2004-2006

Ministero dell'Istruzione, Università e Ricerca
Sistemi supramolecolari per la costruzione di macchine molecolari, conversione dell’energia, sensing e catalisi
PRIN Project, 2006 call, 2007-2008
   
Ministero dell'Università e della Ricerca Scientifica e Tecnologica
Manipolazione molecolare per macchine nanometriche
FIRB Project, 2001 call, 2001-2006

European Commission - 5th Framework Programme
Molecular-level devices and machines    
Human Potential Programme Project, 2000-2004

Ministero dell'Università e della Ricerca Scientifica e Tecnologica
Sistemi molecolari e supramolecolari per l'elaborazione di informazioni
Project for young researchers (coordinator), 2000